1. Field of the Invention
The present invention relates to a light emitting diode (LED) package, and more specifically, to a chip-on-board (COB) LED package which can reduce a manufacturing cost.
2. Description of the Related Art
LED is a semiconductor element which converts electric energy into light energy and is composed of a compound semiconductor which emits a specific wavelength of light depending on an energy bandgap. LED is used in optical communication, display (mobile display, computer monitor), backlight unit (BLU) for LCD and so on.
When LED is used for a mobile display and a computer monitor, a light source is positioned on one surface of a screen, and light is uniformly distributed through a light guide plate. Therefore, the number of LED chips to be used is small.
On the other hand, when LED is used as a backlight source for large-sized TVs, a light source should be disposed under the screen. Therefore, the number of LED chips to be used increases, compared with when the light source is positioned on one surface of the screen. In general, several hundreds to several thousands of LED chips are used. In this case, a COB method is used, in which several hundreds to several thousands of LED packages are mounted on a substrate, or LED chips are directly mounted on a printed circuit board (PCB).
FIG. 1 is a cross-sectional view of a conventional LED package serving as a backlight source, in which LED chips are directly mounted on a PCB.
As shown in FIG. 1, the conventional LED package 10 includes a PCB 11 and a plurality of LED chips 13 mounted on the PCB 11.
On the PCB 11, a plurality of electrode pads 12 are formed so as to be electrically connected to the LED chips 13 through wires 15. The electrode pad 12 is formed of Au (gold) or Ag (silver).
On the LED chip 13, a molding compound 17 is formed so as to protect the LED chip 13 and the wire 15.
The conventional LED package 10 constructed in such a manner generates light by using an electrical signal supplied through the PCB 11.
In the conventional LED package 10, however, the electrode pads 12 formed on the PCB 11 are formed of a metallic material such as Au or Ag, and the number of LED chips 13 mounted on the PCB 11 reaches several hundreds to several thousands. Therefore, the number of electrode pads 12 which are to be formed in accordance with the number of LED chips 13 inevitably increases, thereby increasing the manufacturing cost.
Further, since the heat generated from the LED chips is not effectively radiated, the brightness of the LED chips decreases, and thus the lifespan thereof decreases.